Revert "synchronizes pendingVolatiles"

This reverts commit 000c18a8fac60065747652368dadcd7850532f3f,
because Symbol.isStable is independent from Type.isVolatile
since fada1ef6b315326ac0329d9e78951cfc95ad0eb0.

5 files changed, 7 insertions, 18 deletions

diff --git a/src/reflect/scala/reflect/internal/Symbols.scala b/src/reflect/scala/reflect/internal/Symbols.scala
index 28d980bcfd..b00380f962 100644
--- a/src/reflect/scala/reflect/internal/Symbols.scala
+++ b/src/reflect/scala/reflect/internal/Symbols.scala
@@ -796,7 +796,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      *
      * Stability and volatility are checked separately to allow volatile paths in patterns that amount to equality checks. SI-6815
      */
-          def isStable        = isTerm && !isMutable && !(hasFlag(BYNAMEPARAM)) && (!isMethod || hasStableFlag)
+    final def isStable        = isTerm && !isMutable && !(hasFlag(BYNAMEPARAM)) && (!isMethod || hasStableFlag)
     final def hasVolatileType = tpe.isVolatile && !hasAnnotation(uncheckedStableClass)
 
     /** Does this symbol denote the primary constructor of its enclosing class? */
diff --git a/src/reflect/scala/reflect/internal/Types.scala b/src/reflect/scala/reflect/internal/Types.scala
index e9230aceee..7fc7af1b71 100644
--- a/src/reflect/scala/reflect/internal/Types.scala
+++ b/src/reflect/scala/reflect/internal/Types.scala
@@ -1976,12 +1976,12 @@ trait Types
     def apply(value: Constant) = unique(new UniqueConstantType(value))
   }
 
-  private var _volatileRecursions: Int = 0
-  def volatileRecursions = _volatileRecursions
-  def volatileRecursions_=(value: Int) = _volatileRecursions = value
-
-  private val _pendingVolatiles = new mutable.HashSet[Symbol]
-  def pendingVolatiles = _pendingVolatiles
+  /* Syncnote: The `volatile` var and `pendingVolatiles` mutable set need not be protected
+   * with synchronized, because they are accessed only from isVolatile, which is called only from
+   * Typer.
+   */
+  private var volatileRecursions: Int = 0
+  private val pendingVolatiles = new mutable.HashSet[Symbol]
 
   class ArgsTypeRef(pre0: Type, sym0: Symbol, args0: List[Type]) extends TypeRef(pre0, sym0, args0) {
     require(args0.nonEmpty, this)
diff --git a/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala b/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
index b3b20a888e..3a41edd28b 100644
--- a/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
+++ b/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
@@ -32,8 +32,6 @@ trait JavaUniverseForce { self: runtime.JavaUniverse  =>
     // inaccessible: this._skolemizationLevel
     // inaccessible: this._undoLog
     // inaccessible: this._intersectionWitness
-    // inaccessible: this._volatileRecursions
-    // inaccessible: this._pendingVolatiles
     // inaccessible: this._subsametypeRecursions
     // inaccessible: this._pendingSubTypes
     // inaccessible: this._basetypeRecursions
diff --git a/src/reflect/scala/reflect/runtime/SynchronizedSymbols.scala b/src/reflect/scala/reflect/runtime/SynchronizedSymbols.scala
index 1a232c8de1..d7e3d3c84b 100644
--- a/src/reflect/scala/reflect/runtime/SynchronizedSymbols.scala
+++ b/src/reflect/scala/reflect/runtime/SynchronizedSymbols.scala
@@ -71,8 +71,6 @@ private[reflect] trait SynchronizedSymbols extends internal.Symbols { self: Symb
       }
     }
 
-    override def isStable: Boolean = gilSynchronized { super.isStable }
-
 // ------ creators -------------------------------------------------------------------
 
     override protected def createAbstractTypeSymbol(name: TypeName, pos: Position, newFlags: Long): AbstractTypeSymbol =
diff --git a/src/reflect/scala/reflect/runtime/SynchronizedTypes.scala b/src/reflect/scala/reflect/runtime/SynchronizedTypes.scala
index de78e527a7..eb164777b4 100644
--- a/src/reflect/scala/reflect/runtime/SynchronizedTypes.scala
+++ b/src/reflect/scala/reflect/runtime/SynchronizedTypes.scala
@@ -50,13 +50,6 @@ private[reflect] trait SynchronizedTypes extends internal.Types { self: SymbolTa
   private lazy val _intersectionWitness = mkThreadLocalStorage(perRunCaches.newWeakMap[List[Type], sWeakRef[Type]]())
   override def intersectionWitness = _intersectionWitness.get
 
-  private lazy val _volatileRecursions = mkThreadLocalStorage(0)
-  override def volatileRecursions = _volatileRecursions.get
-  override def volatileRecursions_=(value: Int) = _volatileRecursions.set(value)
-
-  private lazy val _pendingVolatiles = mkThreadLocalStorage(new mutable.HashSet[Symbol])
-  override def pendingVolatiles = _pendingVolatiles.get
-
   private lazy val _subsametypeRecursions = mkThreadLocalStorage(0)
   override def subsametypeRecursions = _subsametypeRecursions.get
   override def subsametypeRecursions_=(value: Int) = _subsametypeRecursions.set(value)